In the field of carpentry, plastering and drywall construction a smooth finish is generally produced by sanding the surface. In drywall construction, for example, the abutting edges of the plasterboard sheets are covered with a paper or fabric tape and the sheets are coated with a layer of plaster. After the plaster has dried, it is sanded until a sufficient quantity of plaster is removed so that all the sheets have a continuous smooth surface. The application of the drywall is generally performed near the end of the construction project. Therefore, it is important that the fine plaster dust removed by the sander be collected and confined so that the dust does not enter the embient air and interfere with such subsequent construction stages as painting, counter work and wall papering. During remodeling and repair, it is especially important to collect and confine the dust to a small area.
There are currently available several sanding devices and particularly electrical motor driven sanders that employ a vacuum chamber for collecting and depositing the dust in a collector chamber.
For the most part these vacuum sanders are too large and heavy to allow extended periods of operation, and they are not designed to be mounted on the end of an extended vacuum tube or rod. A sander mounted on such a vacuum tube or rod is especially useful for sanding upper wall sections and the ceiling.
A search of the prior art did not disclose any patents that read on the claims of the instant invention. However, the following U.S. patents are considered related and indicative of the state of the art.
______________________________________ U.S. Pat. No. INVENTOR ISSUED ______________________________________ 4,062,152 Meher 13 December 1977 3,826,045 Champayne 30 July 1974 3,815,292 Hutchins 11 June 1974 3,646,712 Quintana 7 March 1972 ______________________________________
The Meher patent discloses a vacuum sander that includes an abrasive sheet mounted on the front surface of a backing plate. A manifold covers the rear surface of the backing plate, and the interior of the manifold communicates with the abrasive sheet through a plurality of bores in the plate. The manifold is maintained at reduced pressure by a partial vacuum communicating with the manifold through a tubular handle connected to the vacuum source. The residue produced by using the sander is collected by the vacuum in the manifold and conveyed to the vacuum source through the handle.
The Champayne patent discloses a vacuum unit for removing abraded dust through a suction line communicating with a dust confining shroud. The shroud overlies and extends around the abrading pad of the machine, and is connected to a suction line manifold. The manifold, in turn, is connected to a flexible hose that leads to a vacuum source.
The Hutchins patent discloses an abrading tool having an aspirator for creating a partial vacuum that acts to withdraw abraded particles to a collector. The aspirator includes a conduit forming a passage into which air and entrained particles are drawn. The air is drawn through an opening, with air inlet means that directs a flow of air into the passage and across the opening to induce the desired movement of the particles.
The Quintana patent discloses a dust-removing attachment device for rotary disk power grinders or sanders. The device maintains a continuous current of air over and around the grinding/sanding surface to capture and withdraw dust particles into a vacuum chamber. The exhaust air from a vacuum cleaner tank is directed through a first plenum to discharge forcefully about the rotary disk at one side. A vacuum plenum open at the other side of the disk and leading to the input of the vacuum cleaner maintains a strong current of dust-capturing circulating air.